Ejemplo n.º 1
0
        public void FibornacciMinHeap_Test()
        {
            int nodeCount = 1000 * 10;
            //insert test
            var tree = new FibornacciMinHeap <int>();

            for (int i = 0; i <= nodeCount; i++)
            {
                tree.Insert(i);
            }

            for (int i = 0; i <= nodeCount; i++)
            {
                tree.DecrementKey(i, i - 1);
            }

            int min = 0;

            for (int i = 0; i <= nodeCount; i++)
            {
                min = tree.ExtractMin();
                Assert.AreEqual(min, i - 1);
            }

            //IEnumerable tests.
            Assert.AreEqual(tree.Count, tree.Count());

            var rnd        = new Random();
            var testSeries = Enumerable.Range(0, nodeCount - 1).OrderBy(x => rnd.Next()).ToList();

            foreach (var item in testSeries)
            {
                tree.Insert(item);
            }

            for (int i = 0; i < testSeries.Count; i++)
            {
                var decremented = testSeries[i] - rnd.Next(0, 1000);
                tree.DecrementKey(testSeries[i], decremented);
                testSeries[i] = decremented;
            }

            testSeries.Sort();

            for (int i = 0; i < nodeCount - 2; i++)
            {
                min = tree.ExtractMin();
                Assert.AreEqual(testSeries[i], min);
            }

            //IEnumerable tests.
            Assert.AreEqual(tree.Count, tree.Count());
        }
Ejemplo n.º 2
0
        /// <summary>
        /// Get shortest distance to target
        /// </summary>
        /// <param name="graph"></param>
        /// <param name="source"></param>
        /// <param name="destination"></param>
        /// <returns></returns>
        public ShortestPathResult <T, W> GetShortestPath(WeightedDiGraph <T, W> graph, T source, T destination)
        {
            //regular argument checks
            if (graph == null || graph.FindVertex(source) == null ||
                graph.FindVertex(destination) == null)
            {
                throw new ArgumentException();
            }

            //track progress for distance to each Vertex from source
            var progress = new Dictionary <T, W>();

            //trace our current path by mapping current vertex to its Parent
            var parentMap = new Dictionary <T, T>();

            //min heap to pick next closest vertex
            var minHeap = new FibornacciMinHeap <MinHeapWrap <T, W> >();
            //keep references of heap Node for decrement key operation
            var heapMapping = new Dictionary <T, FibornacciHeapNode <MinHeapWrap <T, W> > >();

            //add vertices to min heap and progress map
            foreach (var vertex in graph.Vertices)
            {
                //init parent
                parentMap.Add(vertex.Key, default(T));

                //init to max value
                progress.Add(vertex.Key, operators.MaxValue);

                if (vertex.Key.Equals(source))
                {
                    continue;
                }

                //construct heap for all vertices with Max Distance as default
                var wrap = new MinHeapWrap <T, W>()
                {
                    Distance = operators.MaxValue,
                    Target   = vertex.Key
                };

                var heapNode = minHeap.Insert(wrap);
                heapMapping.Add(vertex.Key, heapNode);
            }

            //start from source vertex as current
            var sourceVertex = graph.Vertices[source];
            var current      = new MinHeapWrap <T, W>()
            {
                Distance = operators.DefaultValue,
                Target   = source
            };

            //until heap is empty
            while (minHeap.Count > 0)
            {
                //no path exists, so return max value
                if (current.Distance.Equals(operators.MaxValue))
                {
                    return(new ShortestPathResult <T, W>(null, operators.MaxValue));
                }

                //visit neighbours of current
                foreach (var neighbour in graph.Vertices[current.Target].OutEdges)
                {
                    //new distance to neighbour
                    var newDistance = operators.Sum(current.Distance,
                                                    graph.Vertices[current.Target].OutEdges[neighbour.Key]);

                    //current distance to neighbour
                    var existingDistance = progress[neighbour.Key.Value];

                    //update distance if new is better
                    if (newDistance.CompareTo(existingDistance) < 0)
                    {
                        progress[neighbour.Key.Value] = newDistance;
                        heapMapping[neighbour.Key.Value].Value.Distance = newDistance;

                        //decrement distance to neighbour in heap
                        minHeap.DecrementKey(heapMapping[neighbour.Key.Value]);

                        //trace parent
                        parentMap[neighbour.Key.Value] = current.Target;
                    }
                }

                //next min vertex to visit
                current = minHeap.ExtractMin();
            }

            return(tracePath(graph, parentMap, source, destination));
        }
Ejemplo n.º 3
0
        public ShortestPathResult <T, W> GetShortestPath(WeightedDiGraph <T, W> graph, T source, T destination)
        {
            if (graph == null || graph.FindVertex(source) == null ||
                graph.FindVertex(destination) == null)
            {
                throw new ArgumentException();
            }

            var progress = new Dictionary <T, W>();

            var parentMap = new Dictionary <T, T>();

            var minHeap     = new FibornacciMinHeap <MinHeapWrap <T, W> >();
            var heapMapping = new Dictionary <T, FibornacciHeapNode <MinHeapWrap <T, W> > >();

            foreach (var vertex in graph.Vertices)
            {
                parentMap.Add(vertex.Key, default(T));

                progress.Add(vertex.Key, operators.MaxValue);

                if (vertex.Key.Equals(source))
                {
                    continue;
                }

                var wrap = new MinHeapWrap <T, W>()
                {
                    Distance = operators.MaxValue,
                    Target   = vertex.Key
                };

                var heapNode = minHeap.Insert(wrap);
                heapMapping.Add(vertex.Key, heapNode);
            }

            var sourceVertex = graph.Vertices[source];
            var current      = new MinHeapWrap <T, W>()
            {
                Distance = operators.DefaultValue,
                Target   = source
            };

            while (minHeap.Count > 0)
            {
                if (current.Distance.Equals(operators.MaxValue))
                {
                    return(new ShortestPathResult <T, W>(null, operators.MaxValue));
                }

                foreach (var neighbour in graph.Vertices[current.Target].OutEdges)
                {
                    var newDistance = operators.Sum(current.Distance,
                                                    graph.Vertices[current.Target].OutEdges[neighbour.Key]);

                    var existingDistance = progress[neighbour.Key.Value];

                    if (newDistance.CompareTo(existingDistance) < 0)
                    {
                        progress[neighbour.Key.Value] = newDistance;
                        heapMapping[neighbour.Key.Value].Value.Distance = newDistance;

                        minHeap.DecrementKey(heapMapping[neighbour.Key.Value]);

                        parentMap[neighbour.Key.Value] = current.Target;
                    }
                }

                current = minHeap.ExtractMin();
            }

            return(tracePath(graph, parentMap, source, destination));
        }
Ejemplo n.º 4
0
        public void FibornacciMinHeap_Test()
        {
            int nodeCount = 1000 * 10;
            //insert test
            var tree = new FibornacciMinHeap <int>();

            var nodePointers = new List <FibornacciHeapNode <int> >();

            for (int i = 0; i <= nodeCount; i++)
            {
                var node = tree.Insert(i);
                nodePointers.Add(node);
            }

            for (int i = 0; i <= nodeCount; i++)
            {
                nodePointers[i].Value--;
                tree.DecrementKey(nodePointers[i]);
            }
            int min = 0;

            for (int i = 0; i <= nodeCount; i++)
            {
                min = tree.ExtractMin();
                Assert.AreEqual(min, i - 1);
            }

            nodePointers.Clear();

            var rnd        = new Random();
            var testSeries = Enumerable.Range(0, nodeCount - 1).OrderBy(x => rnd.Next()).ToList();


            foreach (var item in testSeries)
            {
                nodePointers.Add(tree.Insert(item));
            }

            min          = tree.ExtractMin();
            nodePointers = nodePointers.Where(x => x.Value != min).ToList();
            var resultSeries = new List <int>();

            for (int i = 0; i < nodePointers.Count; i++)
            {
                nodePointers[i].Value = nodePointers[i].Value - rnd.Next(0, 1000);
                tree.DecrementKey(nodePointers[i]);
            }

            foreach (var item in nodePointers)
            {
                resultSeries.Add(item.Value);
            }

            resultSeries.Sort();

            for (int i = 0; i < nodeCount - 2; i++)
            {
                min = tree.ExtractMin();
                Assert.AreEqual(resultSeries[i], min);
            }
        }
Ejemplo n.º 5
0
        /// <summary>
        /// Search path to target using the heuristic.
        /// </summary>
        public ShortestPathResult <T, W> FindShortestPath(WeightedDiGraph <T, W> graph, T source, T destination)
        {
            //regular argument checks
            if (graph?.FindVertex(source) == null || graph.FindVertex(destination) == null)
            {
                throw new ArgumentException();
            }

            //track progress for distance to each Vertex from source
            var progress = new Dictionary <T, W>();

            //trace our current path by mapping current vertex to its Parent
            var parentMap = new Dictionary <T, T>();

            //min heap to pick next closest vertex
            var minHeap = new FibornacciMinHeap <AStarWrap <T, W> >();
            //keep references of heap Node for decrement key operation
            var heapMapping = new Dictionary <T, AStarWrap <T, W> >();

            //add vertices to min heap and progress map
            foreach (var vertex in graph.Vertices)
            {
                //init parent
                parentMap.Add(vertex.Key, default(T));

                //init to max value
                progress.Add(vertex.Key, operators.MaxValue);

                if (vertex.Key.Equals(source))
                {
                    continue;
                }
            }

            //start from source vertex as current
            var current = new AStarWrap <T, W>(heuristic, destination)
            {
                Distance = operators.DefaultValue,
                Vertex   = source
            };

            //insert neighbour in heap
            minHeap.Insert(current);
            heapMapping[source] = current;

            //until heap is empty
            while (minHeap.Count > 0)
            {
                //next min vertex to visit
                current = minHeap.ExtractMin();
                heapMapping.Remove(current.Vertex);

                //no path exists, so return max value
                if (current.Distance.Equals(operators.MaxValue))
                {
                    return(new ShortestPathResult <T, W>(null, operators.MaxValue));
                }

                //visit neighbours of current
                foreach (var neighbour in graph.Vertices[current.Vertex].OutEdges.Where(x => !x.Key.Value.Equals(source)))
                {
                    //new distance to neighbour
                    var newDistance = operators.Sum(current.Distance,
                                                    graph.Vertices[current.Vertex].OutEdges[neighbour.Key]);

                    //current distance to neighbour
                    var existingDistance = progress[neighbour.Key.Value];

                    //update distance if new is better
                    if (newDistance.CompareTo(existingDistance) < 0)
                    {
                        progress[neighbour.Key.Value] = newDistance;

                        if (heapMapping.ContainsKey(neighbour.Key.Value))
                        {
                            //decrement distance to neighbour in heap
                            var decremented = new AStarWrap <T, W>(heuristic, destination)
                            {
                                Distance = newDistance, Vertex = neighbour.Key.Value
                            };
                            minHeap.DecrementKey(heapMapping[neighbour.Key.Value], decremented);
                            heapMapping[neighbour.Key.Value] = decremented;
                        }
                        else
                        {
                            //insert neighbour in heap
                            var discovered = new AStarWrap <T, W>(heuristic, destination)
                            {
                                Distance = newDistance, Vertex = neighbour.Key.Value
                            };
                            minHeap.Insert(discovered);
                            heapMapping[neighbour.Key.Value] = discovered;
                        }

                        //trace parent
                        parentMap[neighbour.Key.Value] = current.Vertex;
                    }
                }
            }

            return(tracePath(graph, parentMap, source, destination));
        }